Tire sealing compositions that both inflate and seal tires are well known. For example, Magyar et al. U.S. Pat. No. 4,501,825, discloses a tire sealant and inflator composition that includes a resin, a latex sealant, an alkylene glycol, fibers, an alkanol amine, a foaming agent, and water. The composition is admixed with a chlorofluorocarbon propellant/inflator. Other patents which disclose tire sealing compositions include those to Jaspon, U.S. Pat. No. 4,337,332, to Ornum et al. U.S. Pat. No. 4,426,468, and to Kent U.S. Pat. Nos. 4,224,208, 4,137,206, and 4,101,494. All patents and other references mentioned above or hereafter are incorporated by reference as if reproduced in full below. [A propellant/inflator is defined herein as any substance which can propel a solution from a container into an inflatable object, and which will also act to inflate the object.]
Prior art tire sealing and/or inflating compositions use hydrocarbons or chlorofluorocarbons as propellants/inflators. Most hydrocarbon propellants are flammable, and there are difficulties and potential risks associated with using hydrocarbons as inflators. Chlorofluorocarbons, CFCs, are used throughout the world in refrigerators, air conditioners, aerosols, and for blowing foam insulation. CFCs are generally viewed as being non-toxic, non-flammable, and safe for use in proximity to humans. Unfortunately, it has recently been discovered that CFCs have a harmful effect on the ozone layer located in the upper atmosphere; since the ozone layer filters harmful radiation from the Earth's surface, increased incidences of skin cancer are believed to result from reductions in the ozone layer thickness or concentration.
Efforts have been made on an international level to reduce CFC usage; these efforts resulted in The Vienna Convention and its Montreal protocol, which are designed to protect the ozone layer by limiting the amount of CFCs released into the atmosphere. Since not all CFCs regulated by the protocol pose the same threat to the ozone layer, individual compounds are assigned ozone depletion potentials, ODPs. ODPs are a measure of the possible effect of the chlorine released by a CFC on the ozone concentration in the ozone layer. ODPs are calculated from the atmospheric lifetime of the compound, and from the effectiveness of the chlorine released once the compound is decomposed by ultra-violet light. The current aim of the protocol is a phased reduction in total ODP arising from regulated CFCs in steps of 20% and 50%. (See "The Ozone Layer, The Greenhouse Effect," ICI America's Inc., General Chemicals Department, Halocarbon Development Group, Wilmington, Del. 1987.) For example, CFC-11 (otherwise known as F-11, freon-11, arcton, or trichlorofluoromethane) has an ODP of 1.0, as does freon 12 (dichlorodifluoromethane). A compound with an ODP of zero should have no substantial negative impact on the ozone layer.
Recent U.S. legislation, such as the Clean Air Act, has set a timetable for phasing out CFCs. Therefore, it is highly desirable to substitute CFCs with non-ozone depleting, nonflammable compounds wherever possible. Recently, a new nonflammable refrigerant and blowing agent, known as arcton 134a (1,1,1, 2-tetrafluoroethane or R134a) was invented, which has an ODP of zero, yet is non-corrosive and non-toxic. (See Gumprecht U.S. Pat. No. 4,851,595, and Voigt et al. U.S. Patent No. 4,898,645, for processes for the production of 1,1,1,2-tetrafluoroethane.)
It is therefore desirable to replace the chlorofluorocarbon and/or flammable hydrocarbon propellant/inflators used in conventional tire sealing and inflator compositions with a non-flammable substitute such as 134a, which has a low ozone depletion potential. However, numerous problems must be overcome in order to replace chlorofluorocarbon or hydrocarbon propellants/inflators used in existing tire sealant and inflator compositions with a nonflammable, non-ozone depleting propellant/inflator. These problems result from differences between the vapor pressures of existing propellant/inflators and suitable CFC substitutes, poor solvent properties of CFC substitutes, higher diffusion rates of CFC substitutes, and difficulties in obtaining consistent discharge rates throughout the life of tire sealer and inflator products when using a CFC or flammable hydrocarbon substitute.
It is particularly important that any non-flammable, nonozone depleting propellant/inflator used in a tire sealer and inflator composition be capable of storage in canisters which can be safely transported. The U.S. Department of Transportation, DOT, has issued regulations regarding minimum performance characteristics of containers which can be used in interstate transportation. These standards are met by existing containers used for conventional tire sealant/inflator compositions, and any tire sealer/inflator composition made with a non-flammable, non-ozone depleting propellant/inflator must also meet the DOT standards.
However, attempts to substitute R-134a for conventional CFC propellants/inflators have been unsuccessful since R-134a has a vapor pressure at 130.degree. F. which is too great to meet the DOT requirements for use in aerosol cans, such as those which are used for storing and transporting conventional tire sealing and inflating compositions. Further, R-134a is not miscible with aqueous solvents, and therefore, tire sealant/inflator compositions made by replacement of existing hydrocarbon or CFC propellants with R-134a would require vigorous and frequent agitation before and during use to prevent disproportionate dispensing of the sealant.
Tire sealant/inflator cans are frequently stored in the trunks of vehicles, or worse, are exposed to direct sunlight in sealed vehicles in mid-summer. Therefore, internal pressure and can strength are very important safety parameters, which must be considered in producing a tire sealant/inflator composition. The high vapor pressure of R-134a increases the potential that compositions using R-134a will have an even greater vapor pressure than conventional tire sealer and inflator compositions, which could lead to bursting of the containers used to store the compositions.
Hydrofluorocarbons with ODPs of zero, such as 1,1-difluoroethane HFA 152a, ODP=Zero) and 1,1,1,2-tetrafluoroethane, also have relative diffusion rates which are higher than most CFCs; therefore, it was believed that, even if tires or other inflatable objects could be inflated with R-134a or HFA-1 52a, that the tires would not stay inflated due to effusion and/or diffusion of the CFC substitutes into or through the tire rubber.
Thus, there is a need for sealer and inflator compositions which do not utilize flammable propellant/inflators, or use propellant/inflators which harm the ozone layer, and there is a need for sealer and inflator compositions having vapor pressures at elevated temperatures which are sufficiently low to allow storage in containers which meet Department of Transportation requirements for aerosol cans. There is also a need for a non-flammable tire sealing and inflating composition which does not harm the ozone layer, and is homogenous to prevent disproportionate dispensing, and which allows consistent discharge rates and spray characteristics throughout the life of the product. There is a further need for a tire sealing and inflating composition with the foregoing properties which functions over a wide range of temperatures, preferably between 25.degree. F. and 100.degree. F.
Thus, it is a primary object of the present invention to provide a tire sealant and inflator composition which combines a sealant with a non-flammable propellant/inflator having an ozone depletion potential of zero;
It is a further object of the present invention to provide a sealer and inflator composition which contains a biodegradable sealant and a non-flammable, non-ozone depleting propellant/inflator;
It is a further object of the present invention to provide a sealer and inflator composition which utilizes a propellant/inflator having an ozone depletion potential of zero, and which does not have a vapor pressure in excess of 180 psig when the temperature is 130.degree. F.;
It is yet another object of the present invention to provide a sealer and inflator composition containing a nonflammable propellant/inflator with an ODP of zero in an easy to transport container which meets U.S. Department of Transportation requirements; and
It is still yet another object of the present invention to provide a method for inflating inflatable objects, such as tires, with a sealer and inflator composition which is nonflammable and has an ozone depletion potential of zero.
It is yet a further object of the present invention to provide a sealer and inflator composition containing a nonflammable propellant/inflator with an ODP of zero which functions at least between the temperatures of 25.degree. F. and 100.degree. F.